framework try-in app.
- 1. inspect (consult)
- 2. seat/fit
- 3. physiologic adjust (EXTENSION BASE)
- 4. occlusal adjust
- 5. altered cast impression (ext base only)
Pressure indicator made from:
Chloroform and rouge
Do not adjust ________ before consulting with an instructor.
- adjust framework w/ high speed burs
UCLA functional design classifications
- 1. tooth borne: abutment tooth borders edentulous, functional forces tranmitted through abutment
- 2. extension base: distal or anterior extension, force thru abutment & MUCOSA to bone
Differential displacement (PDL vs. Mucosa)
axis of rotation through:
- 1. rest closest to extension base
- 2. farthest rest
- Provide the RPD framework with physiologic relief to allow for its movement along the axis of rotation
- masticatory forces vs. proximal plate/minor connector could bind teeth during RPD functional movements
Why physiologically adjust?
- Establish a safety factor for abutment teeth to minimize the torquing or binding force due to
- (1) the different compressive capacity of hard and soft support
- (2) perspective bone resorption
- Effective preventive measure to protect abutment teeth for long run!
How to physiolgically adjust?
- The framework is placed in the mouth and moved in
- hyperfunction by pressing the denture base connector in the extension area
- Then, grind the high pressure areas.
- Until the framework moves easily with
- 1) the rest at the axis of rotation rolling smoothly without lifting,
- 2) the I-bar moving forward slightly,
- 3) the abutment not being torqued. Be cautious to over-shave the metal or you will lose the retention and stability.
No more adjustments should be made when the metal reaches ____ mm thickness.
Adjustments are made to the framework (rests and minor connectors) until __________
- 1. natural teeth are in contact
- 2. no interference during excursive movements
Altered Cast Procedure
obtain the maximum support possible from the edentulous area of the extension partial denture
How to fabricate an altered cast tray
- framework is placed on the master cast.
- single layer of wax is placed over the edentulous area to provide a space for the impression material.
- Remove some wax from the denture base connector area
- to provide for the mechanical index of the tray acrylic to the metal.
- Lubricate separating medium and apply the tray acrylic
- The acrylic trays are trimmed and polished
- Make 2-3mm space for border molding
- Do not bond to the framework at this point.
- The altered cast tray is connected to the framework using a thin layer of GC Pattern Resin or DuraLay after the physiologic adjustment is complete
Clinical steps of altered cast impression
- 1. checked proper peripheral extension in mouth
- 2. Border molding
- 3. cut back 1 mm for the impression material
- 4. Vent holes near the finish line
- 5. adhesive 2-3 mm exceeding the flange.
- 6. Mix and load
- 7. seat in the mouth ensuring COMPLETE SEATING
- a. rests in the right positions
- b. necessary movements of soft tissues. H
- c. Do not hold the framework in the extension area only.
- 8. Inspect for smoothness, continuity, and void. 9. Trim these excessive impression material exactly at the metal finish line on the tissue surface.
- 1. remove edentulous area from master cast 1-2mm from tooth-tissue junction
- 2. seat framework
- 3. secure w sticky wax
- 4. confirm nothing stone touching impression
- 5. place retention grooves to hold altered areas
- 6. bead and box ready to pour vaccum-mixed stone
Materials for altered cast impression
- Rubber base or metallic paste (ZOE) can be used.
- Do not use ZOE for tissues with gross undercuts